Google Analytics 4 has strict rules for event naming and require you to adhere to those requirements in order to successfully send events.

Per Google's documentation on[event naming](https://support.google.com/analytics/answer/13316687?hl=en&ref_topic=13367860&sjid=2167389739796023681-NA#zippy=%2Cweb){:target="_blank"}, follow these rules when choosing a name for your event:

- Event names are case sensitive. For example, my_event and My_Event are distinct events.

- Event names can include English and non-English words and letters.

- Do not use reserved prefixes and event names.

- Event names must start with a letter. Use only letters, numbers, and underscores. Don't use spaces.

Google Analytics 4 does not accept custom event names that include spaces. Segment replaces spaces in the Event Name in the Custom Event action with an underscore. As a result, you will see custom events snake cased in Google Analytics 4.

Google Analytics 4 is also case sensitive. If you would like all event names to be lowercase, use the`Lowercase Event Name` setting in the Custom Event action. If this setting is disabled, Google will treat event names with different casing as distinct events.For more information, see[Google Analytics 4 Event name rules](https://support.google.com/analytics/answer/13316687?hl=en&ref_topic=13367860&sjid=2167389739796023681-NA#zippy=%2Cweb){:target="_blank"}.

Google Analytics 4 is also case sensitive. If you would like all event names to be lowercase, use the`Lowercase Event Name` setting in the Custom Event action. If this setting is disabled, Google will treat event names with different casing as distinct events.